Fire alarm notification devices (e.g., speakers, horns, bells, chimes, and flashing lights/strobes) are often mounted in weatherproof back boxes (back boxes). These back boxes provide protection from wet, humid, and/or outdoor environments. In general, a back box is an enclosure designed to receive a fire alarm notification device or other device of a fire alarm system such as a smoke or fire detector or a pull station, to list a few examples. The back boxes provide a volumetric region in which wires of the fire alarm devices are connected to interconnect wiring (e.g., power and/or communication) of the fire alarm system.
FIG. 1 illustrates an example of a back box 10, which was manufactured via injection molding. In the illustrated example, the back box 10 includes a back wall 10-b and sidewalls 10-s1, 10-s2, 10-s3, 10-s4, which project from the back wall 10-b. The sidewalls 10-s1 to 10-s4 define a mouth 10-m, which receives the fire alarm device. In the illustrated example, alignment tabs 18a to 18d are positioned on the sidewalls to align the fire alarm device in the mouth of the back box 10. The back box 10 further includes mounting posts (or bosses) 12a and 12b. These mounting posts 12a, 12b project from the back wall 10-b to the mouth 10-m of the back box 10. The mounting posts further include fastener receiving holes 14a and 14b for screws that secure the fire alarm device to the back box 10. The illustrated example further includes sidewall fastener receiving holes 22a and 22b, which receive additional fasteners for securing the fire alarm notification device to the back box 10.
Additionally, the back box 10 often includes other features. Installation tabs 20a, 20b, which include fastener receiving holes 21a, 21b, are used to attach the back box to a surface such as a vertical wall or ceiling. In the illustrated example, the back wall 10-b and sidewalls 10-s1 to 10-s4 include “punch outs” (or knock outs) 16a to 16d for connecting conduits to the back box 10. A gasket 26 sits on a gasket surface 24 to provide a seal between the fire alarm device and the back box 10.